Artificial busy-circuits



Patented. Dec. 13, 1921.

hue/770k Eyyak/ Dan/son M 9* UNITED STATES PATENT OFFICE.

DAWSON M. TAGGART, OF EAST ORANGE, JERSEY, ASSIGNOR TO WESTERN ELEC- TRIC COMPANY INCORPORATED, 015 NEW YORK, N. Y., A CORPORATION OF NEW YORK.

Specification of Letters Patent.

Patented Dec. 13, 1921.

Application filed September 4, 1919. Serial No. 321,534.

:To all whom it may concern:

Be it known that I, DAWSON M. TAGGART, a citizen of the United States, residing at East Orange, in the county of Essex, State of New Jersey, have invented certain new and useful Improvements in Artificial Busy- Circuits, of which the following is a full, clear, concise, and exact description.

This invention relates to a circuit arrangement for use in connection with trunks out-going fromone telephone exchange to another. i

It is the object of this invention to provide means whereby a desired group of trunks may be rendered busy at the office from which they are outgoing under the control of an operator at the oflice at which they terminate.

In multi-oflice systems in which the lines of calling subscribers may be extended to manual operators positions by the use of automatic switches, it will frequently occur that several groups of trunks which are served'by the same. automatic switches extend to the same manual ofiice, where they may appear at the positions of adjacent 0perators. During the rush hours of the day, all of these groups of trunksiwill probably be in use, but during the light load hours, the number of operators at the manual exchange will be materially reduced. It is, therefore, desirable that when the operators leave their positions, they may render the groups of trunks which respectively have access to their positions busy, so that the only group of trunks which may be seized contains trunks leading to a position at which there wiil be an operator.

to such position from the mechanical office.

It is obvious that when a large number of mechanical offices have access to one position, that the number of pairs of conductors extending back to the mechanical ofiices becomes an item of considerable importance in .view of the high cost of telephone cable.

A feature of the invention is the manner in which a group of trunks may be made artificially busy under the control of an operator at the distant end of such trunks, the control being over the talking conductors of an one of such trunks.

A urther feature of the invention resides in thefactthat the release of the artificial busy condition may be controlled over the conductors of any trunk in the group of trunks which has been rendered busy.

It is thought that the invention will be best understood from the following detailed description, reference being had to the ac companying drawings.

In the drawings, Figure 1 shows a group of trunks extending from an automatic office to a manual ofiice and shows the apparatus by means of which the busy condition of the trunks may be controlled. The dotted rectangle in the lower right-hand portion of the drawing shows apparatus at a wire chiefsor other attendants position.

In practice, the trunks would terminate at themanual office in plugs and the number of the desired line will be indicated to the operator by means of an indicator. A circuit arrangement of this type is shown in patentto A. Lundell and F. A. Stearn, No. 1,345,016, granted June 29, 1920. For the sake of simplicity, it has been assumed that the trunks terminate at the manual office in a jack 14 and that from this point connection may be made by a double plug ended cord. In practice, ringing current will be applied when the assignment key would be depressed in conjunction with a ringing key, common to the cords of the position. nthe present instance, it has been assumed that ringing current will be applied through the tip and ring conductors of a plug which may be inserted in the jack at themanual office of the trunk.

The first trunk of the group is indicated by conductors 3 and 4. The second trunk of the group is indicated by conductors 6 and 7. The third trunk of the group is represented by conductors 9 and 10. Other trunks of the group, which may be of any desired size, would extend upward on the drawing.

. Since their interconnection with the remaining trunks of the group would be the same as the interconnection of the first, second and third trunks, it has not been considered necessary to show more trunks.

It will first be assumed that the idlecon dition oftrunks is indicatel by the presence of grounded battery on the test terminals of such trunks. When a trunk is seized, the

sleeve relay of such trunk is energized and locks up through its left-hand armature.

Ground through the test brush of theswltch which has seized suchtrunkwill then render this trunk busy to other testing switches. Assuming now that the operator at the manual office at whose position the trunks shown in the drawing terminate, desires to make a group of trunks busy, she will insert plug "12 into the jack of the first ,idle trunk and applyringing current to the talking conductors thereof by means of a ringing key (not shown). Assuming that the first trunk is idle, a circuit will'then be completed from the source of ringing current 13, ring conductors of plug 12 and jack 14L, conductor 41, outer'right-hand armature and back contact of sleeve relay 15, winding of relay 16, inner right-hand armature and back contact of sleeve relay 15, conductor3, tip contacts of jack 1 1- and plug 12 to ground. Relay'16 is energized in response to the application of ringing current and completes'a circuit from grounded battery, rlght-hand armature and front contact of relay l6,winding of relay inner right-hand armatureand back contact of'relay 15, conductor 3, tip contacts 'of plug 1 1 and jack 12 to ground. Thetone over.

this circuit informs the operator that the group of trunks has been made busy, which "has been accomplished at the outer -left-hand armature and front contact of relay 18, whichsupplies ground to the test terminals 21, 22 and 23 of the trunks shown through resistances 241, 25 and 26 and sleeve relays 15, 27 and 28 in multiple. When the operator hears the characteristicbusy tone, she knows that the group of trunks has been made busy and she thereupon removesplug 12 from jack 14, allowing relay 16 to release. The release of relay 16 causes, in turn, the

I de'e'nergization of relay 1 is tobe observed that relay 18 uponenergizat1on,'prepared a circuit'for'relay 19, this circuit extending from grounded battery, winding of relay 18, right-hand armature and front contact of relay 18 and the which ing of relay 19 to ground. However, due to the presence of ground on the inner right- 4 hand armature and front contact of relay 1r, relay 19 was short-clrcuited and was not en- .ergized at this time. As soon, howevenas relay l7 deenergizesthe shunt is removed from about the winding of relay 19 and this relay energizes. Relay 19 upon energization completes a circuit from grounded battery, lamp 29, right-hand armature and front contact ofrelay19, c0ntaets 30 and 31 of a locking key, through the winding of themagnet of a night-alarm bell indicated at 32 to ground. The ringing of the bell attracts the attention of ,the'Qwire-chief andjupon observing the lighted lamp 29, she depresses the locking key associated with such lamp. The operation'ofth'e key opens the circuit for the alarm bell but allows the lamp to burn dimly due to the introduction of a resistance 33 in the V circuit of lamp 29. The circuit of lamp 29" now extends through'the key contacts 30 and 34- and resistance 33 to ground.-

NVhen the operator desires to again make the group of trunks available for use by automatic switches, she again inserts plug 12 into the'jack of the first trunkand applies ing current as before: Relay 16 is again energized and causes in turn "the energization of relay 17. Relay 17 upon energization completes a circuit from grounded battery,

outer right-hand armature and front contact. of relay 17, inner left-hand armature andv front contact of'relay 19, the winding ofrelay 19 to ground. Relay 19 is maintained energized inthis circuit,but due to the presence of ClHQCtbat-tQIY relay 18 is shunted down and in releasing, removes the busy con dition from the test terminals of the trunks. An idle tone is supplied was operator atthe manualofiicefrom a source of idle tone potential 35,inner left-hand armature and back contact of relay 18,1eft-hand armature and front contact of relay 17, inner left-hand armature and "back'cont'act of rela 15, conductor 3, tipcontacts of jack 14 and plug 12 to the operators headset. Upon hearing this characteristic tone, she will understand'that the'group of trunks hasbeen made idle and will remove the plug12 from jack 14, caus-' ing the deenergization'o'f' relay '16 and in turn, the deenergization of relay 17. The

deenergization of relay 17 causes the release of relay 19. This relay, uno n releasing, completes a circuit from grounded battery, lamp 29',righthand armature and back contact of relay 19, closed contacts 36 and 37' of the key, which is in its lockedposition, and the windingof the night-alarm bell magnet 32 to ground. The lamp 29 is lighted brightly inthis circuitand the alarm bell is caused to ring. The wire-chief"ther p re tores the,

- of trunks busy in thesame way as just described.

It should'be observed that if at the time the operator desires to make the group of trunks busy, the first trunk is in use, she will plug into the second trunk, provided that it is idle. In this case rin ing current will be supplied to relay 16 through the right-hand back contacts and armatures of relay 27 and the right-hand front contacts and armatures of relay 15. If the first and second trunks are busy at the time she desires to make the group busy, ringing current will be supplied through the right-hand contacts and armatures of relay 28 and the right-hand front contacts and armatures of relays 27 and 15 since, due to the busy condition of these trunks, their associated sleeve relays will b inan actuated condition.

What is claimed is:

1. In an interoffice telephone exchange system, an office, a distant office, groups of trunk lines extending-from said first office to said distant office, an operators position at said distant office at which one of said groups of trunks terminates, apparatus at said first office to simultaneously render all the trunks of the group busy, and means under the control of an operator to operate said apparatus over the talking conductors of one of said trunk lines.

2. In an interoffice' telephone exchange system, an office, a distant office, groups of trunk lines extending from said first office to said distant office, an operators position at said distant office'at which one of said groups of trunks terminates, apparatus at said first office to simultaneously render all the trunks of the groups busy, and means under the control of an operator to operate said apparatus over the talking conductors of an idle one of said trunk lines.

8. In an interoffice telephone exchange system, a mechanical office, a manual office, groups of trunk lines extending from said mechanical office to said manual office, an operators position at said manual office at which one of said groups of trunks terminates, apparatus at said mechanical office to simultaneously render all the trunks of the group busy, and means under the control of said operator to operate said apparatus over the talking conductors of one of said trunk lines.

4. In an interoffice telephone exchange system a mechanical office, a manual ofiice, groups of trunk lines extending from said mechanical office to said manual ofiice, an operators position at said manual office at which one of said groups of trunks terniinates, apparatus at said mechanical office to simultaneously render all the trunks of the group busy, and means under the control of said operator to operate said apparatus over the talking conductors of an idle one of said trunk lines.

5. In an interoffice telephone exchange system, an ofi ice, a distant office, a group of trunk lines extending from said first office 'to'said distant office, an operators position at said distant office at which said trunks terminate, a relay at said first office to control the busy or idle condition of all the trunks of said group of trunks, and means to enable said operator to control said relay over the talking conductors of one of said trunks.

6. In an interofiice telephone exchange system, an office, a distant office, groups of trunk lines extending from said first office to said distant office, an operators position at said distant office at which one of said groups of trunks terminates, a source of' ringing current at said operators position, apparatus at said first office to render all the trunks of the group busy, and means to operate said apparatus as a result of applying ringing current to the talking conductors of one of said trunk lines.

7. In an interoffice telephone exchange system, an office, a distant office, groups of trunk lines extending from said first office to said distant office, an operators position at said manual office at which one of said groups of trunks terminates, apparatus at said first office to render all the trunks of the group busy, devices under the control of said operator to operate said apparatus over the talking conductors of one of said trunk lines, means to maintain said busy condition when established, and means to remove said busy condition as a result of the ire-operation of said devices.

8. In an interoffice telephone exchange system, an office, a distant office, a group of trunk lines extending from said first office to said distant office, an operators position at said distant office, a relay combination at said first office to control the busy or idle condition of said group of trunks, and means to control said relay combination over the talking conductors of one of said trunk lines.

9. In a telephone exchange system, an office, a distant office, groups of trunk lines extending from said first office to said distant office, an operators position at said distant office at which one of said groups of trunks terminates, apparatus at said first office to control the busy or idle condition of said group of trunks, means under the control of said operator to operate said apparatus over the talking conductors of one of said trunk lines, and means for indicating to said operator, the busy or idle condition of said group of trunk lines.

10. In a telephone exchange system; an

1 office, a distant office, groups of trunk lines extending from-said first office to said distant office, an operatorsrpositlon at sald distant office at which one of said groups of trunks terminates, apparatus at said first apparatus over the talking conduotors or one of said trunk lines, and-"means for supplyinga characteristic audible tone to said operator to indicate the busy or idle conditionof said trunk lines. r In witness whereof, I hereunto subscribe my name this-29th day of August, A. D.

1919. r V DAWSON M. TAGGART. 

